54 
Ohio Hkjlogical Survey 
thickness; rhizoids rarely seen; ajjothecia usually scattered; the disk 
commonly hrown and surrounded hy an entire thalloid margin; exciple 
almost always in ])art or wholly j)lectenchymatous and usually hyaline; 
hy])othecium hyaline helow to pale hrown above, more often plectenchy- 
matous; hymenium hyaline helow to pale- or darker-hrown above; para- 
])hyses hyaline toward the base and tinged with hrown toward the 
slightly enlarged aj^ex, all s|)ecies examined showing some simple ones 
and others one- to several-times mono])odially branched near the apex 
or farther hack, ranging from 60 to 160 mic. long, from 2 to 3.5 mic. 
wide, and from 6- to 14-celled in the si)ecies examined; asci usually 
clavate, 65 to 105 mic. long and 12 to 21 mic. wide, the walls 0.5 to 2 
mic. thick laterally, and 2 to 11 mic. thick at the apex (thicker in Lcpto- 
giiim laccnim) ; si)ores hyaline, becoming muriform, 8 in an ascus in all 
of ours, irregularly arranged. 
On account of the rigid nature of the thallus, due to the presence of 
a t)lectenchymatous cortex, the algal-host colony does not become so 
much enlarged and so plainly gelatinized when moist as does the same 
host when parasitized hy Syiicclwblastiis or Collcina, genera which are 
less rigid because of absence of a cortex. 
KEY TO THE SPECIES OF LEPTOGIUM 
Plectenchymatoiis cortex of several layers of 
cells around the apothecia. 
Spores 4 cells in length. 
Exciple plectenchymatoiis.5. Leptogium plechtenchymum 
Exciple of interwoven hyphge, but often 
more or less plectenchymatoid.4. Leptogium chloromelum 
Spores usually more than 4 cells in length. 
Medulla plainly mycelial.1. Leptogium pulchellum 
Medulla of densely interwoven hyphge, and 
the structure often plectenchymatoid... .3. Leptogium tremelloides 
Plectenchymatoiis cortex of one or rarely two 
layers of cells around the apothecia.2. Leptogium lacerum 
1. Leptogium pulchellum (Ach.) Nyl. Syn. Licit. /: 123. 1858. 
Collcma pulcliclliiin Ach. Syn. Licit. 321. 1814. 
Transforming the algal-host colony into a rather large, suhorbicular 
body, which is 4 to 12 cm. across, 90 to 265 mic. thick and closely adnate, 
with the marginal lobes free and somewhat raised, with the upper surface 
lead-colored and thrown into delicate, plicate wrinkles, with the lower 
